Spring-fork for motorcycles



H. S. YOXALL AND J J. RICHARDSON.

SPRING FORK FOR MOTORCYCLES.

APPLICATION FILED SEPT. 30. 1920.

Patented Nov. 22, 1921.

3 SHEETS-SHEET 1.

H. S. YOXALL AND I. J. RICHARDSON.

SPRING FORK FOR MOTORCYCLES.

APPLICATION FILED SEPT. 30, I920.

Patented Nov. 22, 1921.

3 SHEETS-SHEET 2.

H. S. YOXALL AND J J. RICHARDSON.

SPRING FORK FOR MOTORCYCLES.

APPLICATION FILED SEPT. 30. 1920.

1,397,850, Patented Nov. 22, 1921.

3 SHEETSSHEET 3.

UNITED STATES PATENT OFFICE.

ENGLAND, ASSIGNORS TO BRAMPTON BROTHERS LIMITED, OF BIRMINGHAM,

ENGLAND.

SPRING-FORK FOR MOTORCYCLES.

Specification of Letters Patent.

Patented Nov. 22, 1921.

Application filed September 30, 1920. Serial No. 413,873.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. L., 1313.)

To all whom it may concern..-

Be it known that we, HENRY SMALLWOOD YOXALL and J OHN Jimms RICHARDSON, subjects of the King of Great Britain, residing at Oliver Street Works, Birmingham, in the county of lVarwick, England, have invented certain new and useful Improvements in Spring-Forks for Motorcycles. (for which we have filed applications in Belgium, Se rial No. 231,431, filed July 10, 1920; Great Britain, No. 15,158, dated June 21, 1914;; Great Britain, No. 17,583, dated July 24, 1914;; Great Britain, No. 116,335, dated June 5, 1917; Denmark, Serial No. 2086, filed July 8, 1920; Germany, filed July 9, 1920; Italy, Serial No. 293/2835, filed July 9, 1920, and Switzerland, Serial No. 7115,

- filed July 9, 1920;) and we do hereby declare the following to be a full, clear, and exact description of the same.

Our invention relates to spring forks for motor cycles and refers to that class of such known as link forks, 2'. e., in which the fork is connected to the steering post by links in such manner as to permit the fork to rise and fall relatively to the steering post.

In this type of fork it has been the practice to connect the fork to the post by a pair of links one on each side, long spindles being provided which pass through the links and through a tubular part of the fork and a similar long bearing carried by the steering post. The extremities of these are usually screwed passing through plain holes in the. links and being secured by nuts and spring washers, but it is found in practice that these nuts frequently work loose permitting lateral playbetween the forks and the steering head.

The invention is also applicable to that land of link fork which in addition to the usual pair of links connecting the steering head with the fork, the top of the steering head is connected to the top of the fork by a pair of extensible links, these links also being connected to the fork by a spindle secured to' the links by nuts screwing on its ends One feature of the present invention consists in an'arrangement for preventing lateral play between either pair of links and the fork and iniaccordance therewith the spindles employed for securing the pairs of links to the fork are screwed right and left hand at their extremities and engage wlth correspondingly screwed holes in the links whereby the links are positively held against lateral movement and may be adjusted to compensate for wear.

The spindles may be provided with squared or equivalent extremities whereby they may be easily rotated for effecting an adjustment.

Another part of our invention relates to the construction of the extensible links connecting the steering head with the forks and in accordance therewith we employ a pair of links each provided with an eye or its equivalent upon one end and an abutment at the other end, a slide being provided upon each link and a spring being provided upon each side of the two slides, a pin or spindle connecting the two slides together and forming a pivot pin inthe linkage system.

A further part of our invention relates to the arrangement of the springs upon the extensible links and consists in arranging upon said links a light spring or springs which are adapted to be compressed or put into tension first, after which a main spring or springs comes into play to absorb the main shock or load, minor shocks or a light load being taken by the light spring or springs.

The arrangement may include one or more abutments which are provided and arranged to come into action after the light spring has been compressed.

Referring to the drawings Figure 1 is a perspective view of a form of spring fork made in accordance with our invention.

Fig. 2 is a plan view partly in section showing one pair of links with the spindles and bearings arranged according to this invention.

Fig. 3 is a plan view of the upper link members.

Fig. 4c is a longitudinal section through one of the upper link members.

' Fig. 5 is a plan view of the upper links showing another arrangement of springing.

Fig. 6 is a longitudinal section through one of the links shown in Fig. 5.

Figs. 7 and 8 are elevations showing two modified forms of the upper links.

In carrying our invention intopractice as illustrated upon the accompanyingdrawings the links 11 are of the usual form, but are screw threaded, one link being screwed right hand while the other link is screwed left hand. i

The spindles 16 and 19 are similarly screwed right and left hand to engage with the links, these spindles being provided with a squared or equivalent extremity 6 whereby they may be rotated to draw the links nearer to each other or further from each other in order to get a fine lateral adjustment, so as to prevent lateral movement or shake between the fork proper marked 10 and the steering post marked 5. I The spindles pass through the tubular bearing portions marked 18 and 17, being provided with lock nuts (4 and washers a It will be obvious that the two links can not laterally separate unless the spindle is rotated, and it is practically impossible for such rotation to take place involuntarily owing to the vibration when in use, particularlv if the lock nuts are screwed up tight.

Referring to Figs. 1, 3 ande the links are of round section, being provided at one end with eyes 1, or the equivalent and being screwed at 2 upon the opposite end; On the round portions of each of these links is placed a slide 13 these slides 13 being connected tothe cross sleeve 3 by the spindle 14, the connection permitting an angular movement between the parts 13 and 3. The slides and the spindle form a cross piece and the part 3 forms part of, or is rigidly connected to the fork proper, i. e., the part which rises and falls.

The eyed extremities of the links are at the back, and are connected by the spindle 15 to the lug 4: attached to the steering post clip 5', while the screwed extremities proect forwardly through the slides, which are carried by the fork proper. The springs 6 u are located between the eyed extremities of the links and the rear of the slides, suitable springs '1' being located between the front of the slides and the screwed ends of the links.

The screwed extremities of the links are provided with an adjustment nut 8 and a lock nut 9 the former of which may be round and of a considerable diameter to correspond with the diameter of the spring and form an abutment, while the other nut may be a smaller hexagonal one.

"The fork 10 is further carried by the links 11 which are mounted by the spindle 16 upon lugs 17 formed integral with the bottom of the steering post, the links being also connected to the cross piece 18 of the fork by the spinclle19, and the drawings show springs 12 controlling the oscillation of the linkage, but the invention is not necessarily confined to such an arrangement of these springs. The springs6 are brought into ac:

tion when the lower end of the fork rises forwardly, the fork rocking about spindle 19, and they serve as main springs in all cases where the resultant of the forces acting at the hub acts in a direction passing forwardly of the front end of the lower linkage element, the springs 7 serving to absorb the reactions. 7

By this partof our invention we provide a fork of the class specified, having greater lateral stability than forks of thiskind as heretofore made, while means are readily provided for adjustment due to wear.

In the form of spring forki for motor cycles shown in Figs. 5 and 6,'the upper links are in the form of plungers 1 pivoted to the steering column 2* of the bicycle and projecting forwardly through sliding member 3 pivoted on the top of the fork proper. Between this sliding member and the pivoted end of the plunger two helically coiled springs 5 6*" are disposed one of which 5 is of greater length and strength than the other one, i. 6., 6, these two springs being preferably separated by a loose disk or floating arbor'l, all being so arranged that light loads or shocks will first compress the light spring, the mainspring coming into action after the light spring has been fully compressed. Y

Preferably the arbor is provided with a projection 8 disposed within the light spring'which may serve to provide an extended bearing for the arbor and which serves to limit the extent to which the light spring may be compressed before the main spring is brought under load. As seen in Fig. 6, the arbor 7* has a projection 8 while the enlarged end 9" of the link 1 has a similar projection 10 which abut together when the light spring has been compressed to the desired extent. Or if the light spring is placed adjacent the slide the projections would be on thearbor and slide or on one of them only.

The extremity of the plunger projecting beyond the slide may carry a single re-action spring 12 as shown by Figs. 5 and 6 or as seen in Figs. 7 and 8 it may'carry two springs 13*, li arranged in similar manner to the main springing system herein? before described, the one spring 13 then serving to absorb the light re-action shocks while the other spring 14* absorbs the main re-action shocks. A similar arrangement of projections on the sliding arbor and nut 15 may be used. i

In place of the helical compression springs described any other suitable form of springing may be employed such as rubber buffers 18 as shown by Fig. 8.

Whatwe claim then is 1. A spring fork for motor cycles comprising a fork,- a steering post, a pair of pivoted links connecting said post to the fork, a spring adapted to resist movement of the links about their pivots, a pair of resilient links connecting said post to the fork, each link of said pair having means for attaching it to the steering post upon one end and an abutment at the other, a slide upon each link, a spring upon each side of the two slides and a spindle connecting the slides together and forming a pivot pin in the linkage system.

2. A spring fork for motor cycles comprising a fork, a steering post, a pair of pivoted links connecting said post to the fork, a spring adapted to resist movement of the links about their pivots, apair of resilientlinks connecting said post to the fork, each link of said pair having an eye upon one end and an abutment at the other, a slide upon each link, a spring upon each side of the two slides, a spindle connecting the slides together and forming a pivot pin in the linkage system, a pin located in said eyes, and a transverse sleeve on the steering post mounted on said pin between the links.

A spring fork for motor cycles comprising a fork, a steering post, a pair of pivoted links connecting said post to the fork, a spring adapted to resist movement of the links about their pivots, a pairof resilient links connecting said post to the fork, each link of said pair having means for attaching it to the steeringpost upon one end and an abutment at the other, a slide upon each link, a spring upon each side of the two slides, an extension on each slide having a transverse hole therein, a pin located in said holes connecting the slides together and forming a pivot pin in the linkage system, and a transversesleeve on the fork mounted on said pin between the slides.

4. A spring fork for motor cycles comprising a fork, a steering post,; a pair of pivoted links connecting said post to the fork, a spring adapted to resist movement of the links about their pivots, a pair of resilient links connecting said post to the fork, each link of said pair having means for attaching it to the steering post upon one end and an abutment at the other, a slide upon each link, a spring upon each side of the two slides, a spindle connecting the slides together and forming a pivot pin in the linkage system, and means for adjusting the pressure of said springs.

5. A spring fork for motor cycles comprising a fork, a steering post, a pair of pivoted links connecting said post to the fork, a spring adapted to resistimovement of the links about their pivots, a resilient linkage element connecting said post to the fork, springs of different strengths on said linkage, the light spring being stressed first when the linkage is flexed .after which the heavier spring-is stressed to absorb the main shocks.

6. A. spring fork for motor cycles comprising a fork, a steering post, a pair of pivoted links connecting said post to the fork, a springcadapted to resist movement of the links about their pivots, a resilient linkage element connecting said post to the fork, two sets of duplex springs associated with said element, one set absorbing the main shocks and the other set absorbing the re-action shocks.

7. A spring fork for motor cycles comprising. a fork, a steering post, a pair of pivoted links connecting said post to the fork, a spring adapted to resist movement of the links about their pivots, a resilient linkage element connecting said post to the fork, springs of different strengths on said linkage, abutments on said linkage to limit the stressing of one of said springs, the light spring being stressed first when the linkage is flexed after which the heavier spring is stressed to absorb the main shocks.

8. A spring fork for motor cycles comprising a fork, a steering post, a pair of pivoted links connecting said post to the fork, a spring adapted to resist movement of the links about their pivots, a spindle upon which said links are mounted, said spindle having screw threads of opposite directions one of which threads engage with each link, whereby the links are positively held against lateral displacement and may be adjusted to compensate for wear.

9. A spring fork for motor cycles comprising a fork, a steernig post, a pair of pivoted links connecting said post to the fork, a spring adapted to resist movement of the links about their pivots, a spindle upon which said links are mounted, said spindle having screw threads of opposite directions one of which threads engage with each link, whereby the links are positively held against lateral displacement and may be adjusted to compensate for wear, and a part on said link shaped for engagement by a tool for rotating the spindle.

In witness whereof we afiix our signatures.

HENRY SMALLWOOD YOXALL. JOHN JAMES RICHARDSON. 

